1. Field of the Invention
The embodiments of the invention generally relate to the formation of porous semiconductor structures and, more particularly, to an etching system and method for forming multiple porous semiconductor regions, having different optical and structural properties, on a single semiconductor wafer.
2. Description of the Related Art
Electrochemical etching of semiconductors (e.g., silicon (Si), silicon carbide (SiC), gallium arsenide (GaAs), etc.) to produce high surface area porous structures is a well controlled and fast technique often utilized by the photonic and semiconductor research and development (R&D) and manufacturing groups. Typically, this electrochemical etching process is performed in the presence of a computer controlled (e.g., a galvanostat controlled) environment so that a constant current is maintained and applied to the entire wafer throughout the electrochemical etching process. Such a constant current ensures uniform etching and, thereby ensures that the resulting wafer has a uniform porous surface (i.e., a surface with uniform optical and structural properties). However, there is a need in the art for an electrochemical etching system with localized etching capability and method that would allow for multiple porous semiconductor regions, having different optical and structural properties, to be formed on a single semiconductor wafer.